1. Field of the Invention
The present invention relates to a centrifugal type fan, which is particularly suitable for use in an air conditioning apparatus of an automobile.
2. Description of a Related Art
Known in a prior art is a multi-blade fan device as disclosed in the Japanese Un-Examined Patent Publication No. 2-146298 and Japanese Un-Examined Patent Publication No. 2-151519, where a fan assembly having a plurality of blades is stored in a fan casing defining an inlet (mouth) for air introduced into the casing by the rotational movement of the fan assembly.
Such a prior art fan device is defective in that its operational noise is high and its fan efficiency is low due to the creation of turbulence in the casing because of the occurrence of a reverse flow or vortex.